In recent years, from the demand for resource saving, an image forming apparatus in which an image is formed with color erasable developer and a color erasing apparatus are introduced. In this color erasing apparatus, heat or light is applied to a recording medium, on which an image is formed with color erasable developer, to erase the color of the developer, and erases the image. Accordingly, the recording medium after the color erase can be re-used.
Here, there arises a problem in handling when an image of a confidential document is formed by the above image forming apparatus. This is because when the color erasable developer is cooled to a very low temperature, color development can again occur. Besides, this is because there is a risk that a readable state occurs even if color development does not again occur.
In this point, an image forming apparatus is proposed in which an image of identification information indicating confidential document is formed on a confidential document, and when the recording medium is reused, when the image forming apparatus detects this identification information, it is used for control of copying.